Police visit to an empty house

Not sure what you mean. You just wait and open the door when the police rings the door bell. They don't go inside, and they will not inspect your furniture. I don't see any issue here, in that regard.

ok, indeed you are in a vicious cycle. Not sure why the shipping company needs a registered address to deliver the goods.

What you could do is to get your initial police clearance done at the airbnb and then get your permit, and then change the address at the city hall. (if the shipping company accepts that).

else, if you already know where you will stay in Brussels, normally the police will call you before coming to schedule the date/time or you will get a paper to make an appointment with them.

@BMM996210 Thank you for your response! Can the initial police clearance be done while we stay in an Airbnb? I've heard the opposite, that they don't accept temporary address

@Jens79 We got a baby so we don't want to wait at the doorbell of an empty house for about 10 days till the police comes